It is a type of fine hair that grows on the bodies of human fetuses as they develop in the womb.
These hairs disappear at birth or shortly after when the hairy hairs replace them. Downy hairs are also naturally fine and transparent but thicker than lanugo hairs.
Downy hairs are hairs that are usually seen on much of the body in childhood.
Scientific analysis of symptoms
As described, lanugo hair develops in fetuses and generally disappears before or just after birth. However, it may be present in adults in some cases, particularly those with eating disorders.
Scientists do not fully understand the role that lanugo plays in developing a fetus.
Scientists do know, however, that lanugo hairs combine with a waxy substance called vernix caseosa to coat the body of a fetus.
As suggested in a 2009 article, this combination of lanugo and vernix hairs, along with other factors, could play a role in producing different hormones within the fetus.
Lanugo appears to play an essential role in the healthy development of a fetus. However, the appearance of lanugo in adults experiencing various diseases is more mysterious.
One theory is that the appearance of lanugo hairs in an adult results from the body trying to insulate itself and preserve heat.
Scientists think this because lanugo often appears in conjunction with conditions that reduce the body’s ability to control its temperature, such as anorexia nervosa.
Causes of lanugo
It is natural for babies to be covered in lanugo, especially if they were born prematurely. However, the reappearance of lanugo in adults is not natural and is a sign of several health conditions.
Downy and lanugo hairs are similar in appearance, and it can be easy to confuse them.
One way to tell if someone is developing lanugo in adults as a symptom of a health condition is to check for the growth of fine hairs in places where they did not grow before, such as on the face or hands.
Lanugo hair growth in an adult is almost always associated with the eating disorder anorexia nervosa.
A 2009 review lists lanugo-like hair growth as one of the skin disorders that almost always occurs in people with severe anorexia.
The same review lists lanugo-like hair growth as the second most common skin symptom due to starvation in people with anorexia.
The authors also mention that lanugo growth is widespread in younger people and appears mainly on the back, upper body, and forearms.
Specific cancer or tumors can cause a person to develop lanugo-like hair, but this is rare.
A 2007 study reported that a person with prostate cancer developed lanugo-like hairs while experiencing the disease, but the inches disappeared after treatment.
The study is far from conclusive. The authors note that the research only dealt with a single individual case. It was the first recorded incident of an association between prostate cancer and lanugo growth that they were aware of.
Older research, dating back to 1978, also reports the case of a man with lung cancer who experienced lanugo-like hair growth on his face, torso, hands, and feet.
These accounts are not conclusive and only involve individual cases. However, they suggest that lanugo growth in adults can sometimes occur in conjunction with various types of cancer.
There are very few reports in the literature on lanugo hair growth associated with cancer.
A 2006 review refers to a study that found a case of lanugo-like hair growth in a person who had celiac disease.
The reviewers described it as the only case of such an association reported in the literature.
Lanugo itself is not a medical condition but rather a natural biological response to specific health conditions and stages of life. As a result, it is not something that requires immediate treatment.
In babies, lanugo is common and not a cause for concern. Babies will naturally lose their hair within a few days to weeks after birth.
Adults who develop lanugo as a symptom of anorexia or other health conditions will lose their lanugo hairs if they are successfully treated.
For people experiencing anorexia, the hair will disappear as they recover through better nutrition.
Lanugo is a natural feature of the body during the growth of a fetus and often lasts shortly after birth. It appears as fine, soft hair on typically “hairless” parts of the body, including areas of the torso, arms, hands, and even the face.
The role of lanugo in the development of fetuses is a bit of a mystery, but it can play an important role in hormonal regulation.
A child will lose its lanugo shortly after birth, and the vellus hairs will replace them. These hairs are fine too and will last the person’s life.